[Effects of prone position ventilation combined with recruitment maneuver on oxygenation and shunt in canines with acute respiratory distress syndrome].
OBJECTIVE
To evaluate the effects of prone position ventilation (PPV) combined with recruitment maneuver (RM) on oxygenation and intrapulmonary shunting in oleic acid-induced acute respiratory distress syndrome (ARDS) in canines while ventilated with lung protective ventilation strategy.


METHODS
ARDS was induced by oleic acid in 24 dogs, and the animals were ventilated with volume controlled ventilation (VCV), 16 cm H2O (1 cm H2O = 0.098 kPa) of positive end-expiratory pressure (PEEP) and small tidal volumes (V(T) 10 ml/kg). All the dogs were randomly divided by random digit table into 4 groups (6 each), a control group (supine position, SP group), a prone position group (PP group), a supine position + RM group (SPRM group), and a prone position + RM group (PPRM group), and then were ventilated by VCV for 4 h. Arterial and mixed venous blood gas analyses were measured. Data were analyzed using the SPSS for windows (version 11.5). Results were expressed as x +/- s. Homogeneity of variance test was performed. The differences in means were calculated using one-way ANOVA. Post-hoc multiple comparisons of means were performed using Least Significant Difference. Nonparametric tests for several independent samples were performed to compare differences between the ranks in the groups studied. P value of < 0.05 was considered statistically significant.


RESULTS
(1) At 15 min, PaO2/FiO2 in the SPRM group, the PP group and the PPRM group [(368 +/- 45) mm Hg (1 mm Hg = 0.133 kPa), (349 +/- 80) mm Hg, ( 423 +/- 43) mm Hg, respectively] was significantly higher than that in the SP group [(269 +/- 72) mm Hg, q = 2.77, 2.23, 4.31, respectively, all P < 0.05]. At 2 h, PaO2/FiO2 in the PP group and the PPRM group [(401 +/- 82) mm Hg, (416 +/- 23) mm Hg, respectively] was significantly higher than that in the SP group [(232 +/- 40) mm Hg, q = 3.99, 4.35, respectively, all P < 0.05]. At 4 h, PaO2/FiO2 in the PPRM group [(384 +/- 68) mm Hg] was significantly higher than that in the SP group [(256 +/- 75) mm Hg], that in the SPRM group [(267 +/-92) mm Hg] and that in the PP group [(284 +/- 83) mm Hg, q = 2.75, 2.56, 2.17, respectively, all P < 0.05]. (2) Intrapulmonary shunt (Q(S)/Q(T)) in the PP group was significantly decreased compared with that in the SP group from 30 min to 2 h [30 min (9.9 +/- 4.4)% vs (15.0 +/- 1.6)%, 1 h (9.7 +/- 4.5)% vs (16.0 +/- 2.0)%, 2 h (8.3 +/- 4.6)% vs (16.2 +/- 1.8)%, q = 2.86, 3.00, 3.65, respectively, all P < 0.05]. The Q(S)/Q(T), in the PPRM group was significantly decreased compared with that in the SP group from 30 min to 4 h [30 min (10.0 +/- 1.0)% vs (15.0 +/- 1.6)%, 1 h (10.4 +/- 2.7)% vs (16.0 +/- 2.0)%, 2 h (10.2 +/- 0.7)% vs (16.2 +/- 1.8)%, 4 h (10.1 +/- 1.1)% vs (15.7 +/- 1.7)%, q = 2.80, 2.67, 2.75, 2.99, respectively, all P < 0.05].


CONCLUSIONS
On the basis of small tidal volume lung and PEEP protective ventilation strategy, combining prone position and recruitment maneuver was more effective and showed a synergistic effect on improving oxygenation and intrapulmonary shunt.
Xu
Qi-Xia
QX
Beijing Institute of Respiratory Medicine, Beijing Chaoyang Hospital Affiliate of Capital Medical University, Beijing 100020, China.
Zhan
Qing-Yuan
QY
Wang
Chen
C
Pang
Bao-Sen
BS
Li
Yi-Ming
YM
D000818:Animals; D001784:Blood Gas Analysis; D004195:Disease Models, Animal; D004285:Dogs; D005260:Female; D008297:Male; D010100:Oxygen / Q000737:chemistry; D011175:Positive-Pressure Respiration / Q000379:methods*; D016684:Prone Position; D012128:Respiratory Distress Syndrome / Q000503:physiopathology* / Q000628:therapy*; D012129:Respiratory Function Tests
D010100:Oxygen